I need help diagnosing a heat problem. I have a 2001 F150 XL. 4.2L Manual controls. The a/c blows nice and cold, but when you put the heat on its not really hot, blows warm air. I changed the blend door actuator,it got a little warmer. Now that winter is around the corner need to figure it out and fix it. The thermostat, water pump, and coolant flushed before I bought it. Could it be the blend door itself, or is there another actuator I'm missing.

 

Your heater core is blocked by sediment over the years there is a powder concentrate you mix in gallon of water pour directly into heater hoses after you disconnect them from wall.this could work to unblock let it soak, blow out with compressed air, however only temp fix. U will need to change heater core, there is a really good video step by step on ytube on how to change it. Took me about 6 hrs to do it.

 

Thanks, I'll give that a try. Could it be something else? The truck was one of my jobs service vechile I bought from them when they bought new ones. They had the heater core flushed out and it never changed? I was told possible blend door, since they did have issues with cracking causing hem not to fully close when switched from cold to warm.

 

It could be that, but. Thought you said it ad even changed.

 

It changed when I changed the actuator, didn't change when the heater core was flushed out.

 

Well check you can turn on ac and change temp setting to see if it goes from cold to hot, f it works well there I would say clogged heater core

 

It does, a/c is ice cold.

 

Clogged heater core!

 

The heater core being clogged what chemical can I use to clean it out with as a temporary fix till I can find time to change it.

 

napa had it, comes in a powder that you mix with water, and pour down the heater hoses

 

The AC is cold but did you try and move the heat setting to warm with the AC on? If so did the AC get warmer when you changed the heat setting? If it did get warmer then it might be a clogged core but if the AC stayed real cold when you put the heat control to warm it is most likely the blend door.

 

The a/c is cold, when I put the dial on heat, it gets warmer just not hot enough.

 

When you changed the blend door actuator did you check with a mirror and/or bent tool to see if the blend door itself turns or the shafts' hole was broken (plastic pieces fallen out when removing actuator? Check the Treater video and they supply blend doors if your up to the job.

Ford F150 '97-'04 - '97 - '04 - F150 - Ford

 

Check the door, turns by hand, no pieces came out when changed actuator. Checked the heater hose when I got to work, & truck at operating temp. One hose was cool to touch, the other was hot to touch.

 

clogged core!!